#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h> //POSIX标准定义的unix类系统定义符号常量的头文件
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 30
void error_handling(char* message);

int main(int argc, char* argv[])
{
    int serv_sock, clnt_sock;//用于服务端的套接字，用于客户端连接的套接字
    char message[BUF_SIZE];//存储输入的字符串
    FILE* fp;
    int read_cnt;
    
    struct sockaddr_in serv_addr, clnt_addr;
    socklen_t clnt_adr_sz;

    if(argc != 2)
    {
        printf("Usage : %s <port>\n", argv[0]);
        exit(1);
    }

    //用只读打开二进制文件
    fp = fopen("file_server.c", "rb");

    //socket()创建socket
    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if(serv_sock == -1)
        error_handling("socket() error\n");

    //bind()分配ip和端口
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(atoi(argv[1]));

    if(bind(serv_sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1)
        error_handling("socket() error\n");
    
    //listen()转换成服务端socket
    if(listen(serv_sock, 5) == -1)
        error_handling("listen() error\n");
    
    //接收连接请求
    clnt_adr_sz = sizeof(clnt_addr);
    clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_addr, &clnt_adr_sz);

    int cnt = 0;
    while(1)
    {
        //将打开的文件放入message中
        read_cnt = fread((void*)message, 1, BUF_SIZE, fp); 
        cnt++;
        //循环发送文件fp，每次发送1*BUF_SIZE的数据，直到发完
        if(read_cnt < BUF_SIZE)
        {
            write(clnt_sock, message, read_cnt);
            break;
        }
        write(clnt_sock, message, BUF_SIZE);
    }
    printf("count of read file : %d\n", cnt);
    //半关闭输出流连接 向客户端传输EOF 表示文件已经传输完毕
    shutdown(clnt_sock, SHUT_WR);
    read(clnt_sock, message, BUF_SIZE);
    //输入流尚未关闭，接收客户端的应答信息
    printf("message from client : %s \n", message);

    fclose(fp);
    close(serv_sock);
    close(clnt_sock);
    return 0;
}

void error_handling(char* message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(-1);
}
